Keep the eyeliner close to the lashes to avoid it taking over the shape if you have...
Deep set eyes are large and set deeper into the skull.
or
Monolids are flat on the surface and don't have much of a crease, if any.
or
Hooded eyes feature an extra layer of skin that droops over the crease, causing the lid to appear smaller.

Apply the eyeliner as thick or thin as you like if you have...
Protruding eyes create the appearance of projected lids in the eye socket area.

Apply the eyeliner the same width from the inner corner to edge if you have...
Wide set eyes are more than one eyeball width apart. To bring your peepers closer together
or
Elongated eyes and you want to create a rounder shape.

Apply the eye liner thicker on the outer edge if you have...
Round eye that you want to elongate
or
Close set eyes are less than one eyeball width apart

Keep the eyeliner close to the lashes to avoid it taking over the shape.